Air Carriers Industry Terminology
A-CDM (Airport Collaborative Decision Making)
A process and data-sharing framework among airports, air traffic control, airlines, and ground handlers to improve predictability and throughput, reduce delays, and optimize use of resources like gates and runways.
“We’re rolling out A-CDM at our main hub to cut taxi-out times.” | “A-CDM data showed de-icing was the bottleneck, not ATC.” | “With A-CDM, airlines, ATC, and the airport share the same departure sequence.”
AOC (Air Operator Certificate)
A regulator-issued authorization that permits an airline to conduct commercial air transport operations, contingent on compliance with safety, maintenance, and operational standards.
“The merger won’t close until the combined carrier gets a single AOC.” | “Our new AOC covers both passenger and cargo operations.” | “Regulators suspended the AOC pending safety audit results.”
AOG (Aircraft on Ground)
An unscheduled maintenance status where an aircraft cannot fly until a defect is rectified, often triggering urgent parts procurement and recovery actions.
“The 737 is AOG in DEN awaiting a hydraulic pump.” | “We initiated AOG logistics to overnight the part.” | “AOG events spike during winter operations.”
Ancillary Revenue
Income outside the base ticket price, such as baggage fees, seat assignments, onboard sales, change fees, priority boarding, lounge access, and co-branded credit card commissions.
“Ancillaries per passenger rose 12% due to seat selection fees.” | “We’ll unbundle baggage to grow ancillary revenue.” | “Credit-card partnerships have become a major ancillary stream.”
ASM (Available Seat Mile)
A capacity metric equal to the number of seats offered times the miles flown; a common denominator for unit cost and revenue measures.
“We increased ASMs 7% by adding capacity on transcons.” | “RASM and CASM both use ASMs as the denominator.” | “Shorter stage lengths can raise CASM for the same ASM growth.”
ATC (Air Traffic Control)
A service that manages aircraft separation and sequencing in airspace and at airports, providing clearances, routing, and traffic flow management.
“ATC flow constraints lowered our OTP today.” | “We filed a different route to avoid ATC delays.” | “ATC slot restrictions impacted our bank.”
Belly Cargo
Freight carried in the lower hold of passenger aircraft, providing additional revenue and leveraging passenger networks for cargo distribution.
“Belly cargo yields are softening as widebody capacity returns.” | “We prioritize belly freight on the night banks.” | “Passenger schedule cuts reduced belly capacity to Asia.”
Block Time
The elapsed time from when an aircraft leaves the gate (blocks out) to when it arrives and parks at the destination gate (blocks in).
“Block time on ORD–LGA increased due to congestion.” | “Pilots are paid based on block hours.” | “We adjusted block to reflect longer taxi-out in winter.”
Carbon Dioxide Equivalent (CO2e)
A standardized metric expressing the climate impact of greenhouse gases in terms of the amount of CO2 that would have the same warming effect.
“We report lifecycle emissions in CO2e.” | “SAF reduces CO2e versus conventional Jet-A.” | “Our 2030 target is a 30% CO2e per RPK reduction.”
CASM (Cost per Available Seat Mile)
Unit cost measured as operating cost divided by ASMs; used to compare cost efficiency across carriers and periods. Often split into CASM ex-fuel and fuel CASM.
“Ex-fuel CASM was flat year over year.” | “Fleet upgauging helped lower CASM.” | “Rising ATC fees pushed CASM higher.”
Code Share
A marketing arrangement where two or more airlines sell seats on the same physical flight, enabling network expansion and seamless itineraries.
“This flight is marketed by us but operated by our partner under a code share.” | “Code shares expand our network without adding metal.” | “We added a code share on the Rome route.”
Crew Pairing
The process of constructing legal, cost-efficient sequences of flight duties for pilots and cabin crew, subject to regulations and contract rules.
“Optimized crew pairing cut our hotel costs 8%.” | “Pairings must respect duty time limits.” | “We built ETOPS-qualified pairings for the new route.”
EFB (Electronic Flight Bag)
A tablet or electronic system that hosts flight manuals, charts, performance tools, and operational applications, replacing or supplementing paper documents.
“The EFB update added performance calculator v3.” | “We went paperless by moving charts to EFBs.” | “EFB connectivity enables real-time weather uplinks.”
ETOPS (Extended-range Twin-engine Operations)
Operational standards allowing twin‑engine aircraft to fly routes far from suitable diversion airports, defined by time thresholds (e.g., ETOPS 120/180/330).
“We’re certified for ETOPS 180 across the North Atlantic.” | “ETOPS alternates drive route planning.” | “Maintenance changes were needed for ETOPS approval.”
Fare Class (Booking Class)
A letter-based inventory bucket linked to fare rules and price points; controls availability, upgrades, and revenue segmentation.
“Revenue management opened more ‘Y’ inventory.” | “Corporate contracts require ‘J’ and ‘C’ fare access.” | “The ‘O’ class promotion spiked bookings.”
FFP (Frequent Flyer Program)
A loyalty scheme awarding points or miles for travel and partner spend, offering elite status, redemptions, and co-branded credit card benefits.
“Miles will be earned based on dollars spent.” | “Elite tiers confer priority services and upgrades.” | “FFP partnerships drive alliance loyalty.”
Fleet Commonality
Using similar or shared aircraft types and systems to reduce training, maintenance, spares, and operational complexity.
“Common type ratings reduce training time.” | “A320-family commonality simplifies spares.” | “Common cabins drive service consistency.”
Full-Service Carrier (FSC)
A network airline offering bundled services (meals, checked baggage on some fares), multiple cabins, and global connectivity via hubs and alliances.
“As an FSC, we offer lounges and through-checked bags.” | “FSCs rely on hub-and-spoke networks.” | “Our FSC arm competes with LCCs on leisure routes.”
GDS (Global Distribution System)
Aggregated reservation platforms (e.g., Amadeus, Sabre, Travelport) used by travel agencies and corporates to access airline schedules, fares, and availability.
“We shifted some content to NDC to bypass GDS surcharges.” | “Corporate bookings still flow through the GDS.” | “Amadeus and Sabre are our primary GDS partners.”
Ground Handling
Ramp and passenger services at airports, including check-in, boarding, baggage, fueling coordination, catering, and aircraft servicing.
“A new ground handler took over ramp at BCN.” | “Turn delays were due to slow ground handling.” | “We insourced ground handling at the hub.”
GSE (Ground Support Equipment)
Equipment used to service aircraft on the ground, such as tugs, belt loaders, ground power units, de-icers, and air start units.
“We replaced diesel GPUs with electric GSE.” | “De-icer uptime is critical GSE in winter.” | “Standardizing GSE cuts maintenance costs.”
Hub-and-Spoke
A network design that concentrates flights at hubs to connect spokes, enabling more city-pair options and higher aircraft utilization.
“Banked hubs boost connectivity.” | “The new spoke feeds our Atlantic bank.” | “We’re depeaking the hub to smooth operations.”
IATA (International Air Transport Association)
The airline trade association that develops global standards (e.g., codes, distribution), coordinates industry initiatives, and facilitates financial settlement.
“We follow IATA’s slot guidelines.” | “IATA codes like LHR and AA are industry standards.” | “IATA BSP simplifies agency settlement.”
ICAO (International Civil Aviation Organization)
A UN specialized agency that issues Standards and Recommended Practices (SARPs) for aviation safety, security, efficiency, and environmental protection.
“Our SMS aligns with ICAO Annex 19.” | “ICAO sets PBN and ADS-B standards.” | “ICAO 3-letter airline codes differ from IATA’s 2-letter codes.”
IFE (In-Flight Entertainment)
Passenger-facing entertainment systems on board, including seatback screens or streaming platforms, often integrated with connectivity and retail.
“We’re moving to wireless IFE streaming.” | “New IFE includes seatback 4K screens.” | “IFE monetization includes paid Wi‑Fi.”
IFR (Instrument Flight Rules)
A set of regulations and procedures for flying by reference to instruments and ATC clearances, used in low-visibility or controlled airspace.
“Weather minima require IFR for the approach.” | “The aircraft filed IFR across the route.” | “IFR training is part of initial pilot qualification.”
Interline Agreement
A bilateral arrangement enabling airlines to accept each other’s tickets and baggage, and to settle revenues for multi-carrier itineraries.
“We interline bags with multiple partners.” | “Interline proration governs revenue split.” | “Without interline, misconnect recovery is harder.”
IOC (Integrated Operations Center)
The airline control hub that manages day-of-operation decisions across dispatch, crew, maintenance control, customer recovery, and network operations.
“The IOC coordinated recovery during the storm.” | “IOC dashboards track crew legality and aircraft status.” | “We consolidated dispatch and crew control into the IOC.”
Jet Fuel Hedging
Using derivatives (swaps, options, collars) or physical contracts to reduce volatility in fuel costs and stabilize unit economics.
“We layered swaps to hedge 50% of next year’s fuel.” | “Call options cap our jet fuel exposure.” | “Our hedge losses reversed as prices fell.”
LCC (Low-Cost Carrier)
An airline model emphasizing low unit costs via high utilization, single-class cabins, dense seating, unbundled fares, and simplified operations.
“The LCC launched a fare war on the route.” | “Ancillary-driven LCC models keep base fares low.” | “Point-to-point networks are typical for LCCs.”
Load Factor
A utilization metric: traffic (RPMs or RPKs) divided by capacity (ASMs or ASKs), indicating what share of seats are filled.
“Load factor hit 87% in Q2.” | “We traded load factor for yield to lift PRASM.” | “Schedule cuts improved load factor on off-peak days.”
MCT (Minimum Connection Time)
The shortest allowable time for a legal connection between flights at an airport, varying by carrier, terminal, and itinerary type.
“We need 45 minutes MCT for domestic-to-domestic.” | “Filed connections violated the MCT for T1–T3.” | “Shorter MCTs improve itinerary attractiveness.”
NPS (Net Promoter Score)
A customer loyalty metric based on the likelihood to recommend (promoters minus detractors), often used to gauge service quality and brand advocacy.
“NPS improved after we reconfigured seats.” | “OTP disruptions drove NPS down.” | “We tie bonuses to quarterly NPS targets.”
On-Time Performance (OTP)
The percentage of flights arriving or departing within a specified threshold of schedule (commonly 15 minutes). Benchmarks include A15/A14 and A0.
“Our A15 arrival OTP was 81%.” | “We’re targeting A0 departures for premium banks.” | “Turn discipline is key to OTP.”
Open Skies Agreement
Air service treaties that liberalize market access, capacity, pricing, and routing (freedoms of the air), enabling more competition and connectivity.
“Open Skies enabled our fifth-freedom service.” | “The bilateral moved from restrictive to Open Skies.” | “Cargo operators benefit from Open Skies freedoms.”
Overbooking
Selling more seats than available to offset expected no-shows, managed by revenue management and governed by consumer protection regulations.
“We overbook by forecasted no-shows to maximize load.” | “VDB offers cleared the oversell.” | “IDBs trigger compensation under DOT rules.”
PAX (Passengers)
Industry shorthand for passengers; used widely in operations, finance, and reporting.
“PAX boarded: 168; no-shows: 4.” | “PAX mix skewed to leisure this quarter.” | “PAX disruptions were mitigated with meal vouchers.”
PRASM (Passenger Revenue per ASM)
A unit revenue metric equal to passenger revenue divided by ASMs, reflecting pricing power and mix on passenger traffic.
“PRASM rose 3% on stronger yields.” | “We saw PRASM pressure in competitive markets.” | “Ancillary fares can lift PRASM indirectly.”
RASM (Revenue per ASM)
Total operating revenue divided by ASMs; includes passenger, cargo, and ancillary, indicating overall unit revenue performance.
“Cargo strength boosted RASM.” | “RASM outpaced CASM, expanding margins.” | “Weak shoulder-season demand hit RASM.”
Revenue Management
The discipline of forecasting demand and optimizing fare availability and pricing by segment and itinerary to maximize revenue per flight/network.
“O&D controls protected high-yield flows.” | “We raised fences to prevent dilution.” | “Dynamic pricing improved shoulder-day pickup.”
RPK (Revenue Passenger Kilometer)
A traffic metric equal to paying passengers multiplied by kilometers flown; the numerator in load factor.
“RPKs grew 10% with international rebound.” | “Load factor = RPK/ASK.” | “RPKs lagged ASM growth on new routes.”
Safety Management System (SMS)
A systematic approach to managing safety risk, including policies, hazard reporting, data analysis, assurance, and promotion across the organization.
“We logged the hazard in the SMS.” | “Data from FOQA feeds our SMS risk assessments.” | “ICAO Annex 19 mandates SMS.”
Schedule Bank
A planned wave of arrivals followed by departures at a hub to maximize passenger connections and aircraft/crew utilization.
“We added a midday bank to improve connectivity.” | “Bank structure drove peak gate demand.” | “Depeaked banks smoothed crew utilization.”
Slot (Airport Slot)
A right or permission to schedule operations at a coordinated airport at a specific time, typically managed by slot coordinators under local rules.
“We secured a slot pair at LHR.” | “The 80/20 use-it-or-lose-it rule was waived.” | “Slot coordination limits new entrants.”
Stage Length
The distance of a flight leg; a driver of unit cost, fuel efficiency, block time, and schedule design.
“Longer stage lengths lower CASM.” | “Short stage lengths hurt fuel burn efficiency.” | “We matched gauge to stage length demand.”
Tail Assignment
The process of assigning specific aircraft (by tail number) to flights, considering maintenance, crew routing, payload limits, and operational constraints.
“Tail swaps recovered the downline delay.” | “Maintenance constraints tightened tail assignment.” | “We optimized tail assignment to cut fuel burn.”
Turnaround Time (TAT)
The ground time between an aircraft’s arrival and subsequent departure; a key driver of aircraft utilization and OTP.
“We target a 35-minute TAT on 737s.” | “GSE availability is critical for TAT.” | “Better cleaning standards extended TAT by 3 minutes.”
ULCC (Ultra-Low-Cost Carrier)
An airline subtype with extreme cost focus and aggressive unbundling, offering very low base fares and charging for most optional services.
“ULCCs rely heavily on ancillary revenues.” | “ULCC seat density raises ASMs per aircraft.” | “Secondary airports support the ULCC model.”
Yield
Average fare per unit of traffic (e.g., passenger revenue per RPM/RPK), reflecting pricing power and customer mix.
“Yield rose despite stable load factors.” | “We traded yield for share on the leisure route.” | “Business mix improves yield in the morning bank.”
ZFW (Zero-Fuel Weight)
The weight of the aircraft and payload excluding usable fuel; critical for performance, balance, and structural limits.
“ZFW plus fuel must stay within MTOW.” | “Payload limits were hit at high ZFW.” | “We re-seated to adjust ZFW center of gravity.”
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